The present invention relates to controls for lawn and garden tractors and more specifically relates to clutch-brake controls for the traction or propel drives of such tractors.
The prior art includes lawn and garden tractors having variable speed traction drives and brakes for such drives. In one type of traction drive brake and clutch control for such tractors, the traction drive is sequentially slowed and then neutralized by operation of a clutch pedal while the brake is engaged by operation of a brake pedal. Also disclosed is a park lock mechanism which is operable to lock the brake pedal in a depressed brake-engage position only after the clutch pedal has been moved to a depressed drive disengage position to thus ensure that the tractor is not driven with the brake held in its engaged position by the park lock mechanism. An example of such controls is illustrated in U.S. Pat. No. 4,037,695 issued to Welck on July 26, 1977.
In another type of design, a single clutch-brake pedal is coupled to the transmission and brake such that, as the pedal is moved through an initial or clutching range of movement, the transmission speed will be decreased to zero which condition remains as the pedal is moved through an intermediate or neutral range of movement. A final or braking range of movement of the pedal results in the brake being applied.
The first of the aforementioned types of control designs has the disadvantage that an operator may apply the brake by depressing the brake pedal before he has fully depressed the clutch pedal. This results in the brakes being applied while the vehicle is being driven thus causing excessive brake wear.
The second of the aforementioned types of control designs has the disadvantage that, if the tractor is being stopped or shifted while ascending or descending a hill, it may continue or begin to roll downhill during movement of the clutch-brake pedal through its clutching and neutral ranges. This may result in the tractor proceeding toward some perilous condition and/or developing such momentum that it is difficult to quickly halt the movement of the tractor.
A further disadvantage of both of the aforedescribed types of controls is that the linkage connecting the pedals to the brake are such that excessively high braking forces may be transferred to the brakes resulting in excessive wear and/or in premature failure of the same.